Definition of "Rat" :

noun: any of various long-tailed rodents similar to but larger than a mouse

noun: a pad (usually made of hair) worn as part of a woman's coiffure

noun: one who reveals confidential information in return for money

noun: a person who is deemed to be despicable or contemptible

"Kill the rat."

noun: someone who works (or provides workers) during a strike

verb: give away information about somebody

verb: catch rats, especially with dogs

verb: give (hair) the appearance of being fuller by using a rat

verb: take the place of work of someone on strike

verb: employ scabs or strike breakers in

verb: desert one's party or group of friends, for example, for one's personal advantage